| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The states of radiance distribution on various skies are quite different from each other. From the practical point of view, it is reasonable that we classify various sky states into three categories (cloudless clear sky, overcast sky, and intermediate sky) and try to standardize the radiance distribution of each sky category.
As for clear sky radiance distribution, the modified equation of Nagata's equation for predicting clear sky luminance distribution was found to be fairly useful for predicting clear sky radiance distribution. However, if we want to get an even better approximate equation, we should devide the radiance of every sky element into the first component caused by primary scattering of direct sunlight and the second component caused by all the other processes, and then we should try to get good approximate equations for predicing respective components.
The pattern of overcast sky radiance distribution is quite similar to the pattern of the luminance distribution on the CIE Overcast Sky. But radiance ratio between the zenith and the sky element near the horizon is approximately 5:2 and this is smaller than the corresponding luminance ratio 3:1 of the CIE Overcast Sky. The radiance of the zenith of overcast sky is approximately propotional to the solar altitude.
All the sky states other than clear and overcast skies are classified into intermediate sky category. Therefore, the radiance distribution pattern of each intermediate sky is usually complicated and quite different from each other. There is almost no regularity about radiance distribution pattern throughout whole intermediate skies. However, the averaged radiance distribution pattern of many intermediate skies of about the same solar altitude has fairly distinct characteristics. The standardization of intermediate sky radiance distribution should be done by taking account of such averaged intermediate skies.
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